1. Field of the Invention
The present invention relates to a timekeeper with a mechanism for measuring settable predetermined periods, comprising a first timer, means for connecting it selectively to the train of the timekeeper, a second timer, a synchronous coupling between the first and second timers, and fly-back means for said timers.
2. Description of the Related Art
Timers of this kind are used particularly for controlling the starts of regattas where the competitors are warned a few minutes in advance of the start time by a gun. A second gun is also fired halfway through the period between the first gun and the third gun which will give the start. This second gun gives competitors the chance to check whether they are synchronized with the official time. This period is usually ten or six minutes so the second gun is fired at exactly the halfway mark, at five or three minutes, respectively.
A timer of this kind has already been proposed in CH 692 523. It has apertures in the dial and a disk having sectors of different colors which appear under the apertures and move as the period is measured. Such a device gives no indication of seconds and cannot be corrected if the timer was not started at the right instant, nor can the countdown time be programmed.
Another proposal, given in WO 02/077725, is a chronograph mechanism capable of operating either in the conventional direct sense, or in the retrograde sense for a countdown. Such a mechanism does not however offer a way of resetting the timer, specifically at the second gun fired before the start of a regatta. In the event of a false start it offers no way of storing the previously programmed period, and after each measurement of a predetermined period has to be reset for the next period to be measured, even if the latter is identical to the previous period.
What is more, with this timer, at the end of the measured predetermined period, the minutes timer does not stop at zero but continues its retrograde movement until stopped.
As can be seen, the systems proposed hitherto all have a number of drawbacks.